In the prior art, proposals have for some considerable time been noted to replace the central drive of looms by means of a single drive motor by a plurality of individual drives, each of which is drive-active in a very specific part region of the loom. So that these individual electromotive rotary drives cooperate appropriately during the weaving operation, synchronizing devices in the manner of electric shafts are required and are known. The invention is concerned particularly with the individual drive of the reed.
Examples of this may be gathered from EP 796 360 B1 and EP 1 312 709 A1. According to EP 796 360 B1, the reed has mounted on or connected to it a reed shaft which is set in a reciprocating pivoting movement via two gears located at its ends. Said gears are located outside the reed width and have input shafts which are set in rotation via reduction gears by electromotive rotary drives located still further outside. The input shafts of the gears thus rotate at a speed other than that of the output shafts of the electromotive rotary drives. Further, it is also assumed that the gears acting on the reed shaft serve not only as conversion gears for achieving a reciprocating pivoting movement of the reed shaft, but, furthermore, also as additional reduction gears. This is customary in the prior art. Moreover, the drive for gripper mechanisms serving for the insertion of the weft threads is derived via rotating cam disks from the input shafts of the gears located outside the reed width. The two electromotive rotary drives of the reed drive are driven in parallel by one or two frequency converters. Synchronization is additionally provided, for which may also serve a connecting shaft which runs at a distance from and parallel to the reed shaft and which runs coaxially with the input shafts of the gears.
In the reed drive of EP 1 312 709 A1, a drive shaft consisting of two parts is provided, which is arranged so as to run parallel to the reed shaft. The electro-motive rotary drive of the reed is arranged in the middle of the two part shafts and also in the middle of the reed-width longitudinal center of symmetry of the loom. Said electromotive rotary drive has at its ends two output shafts which are connected to the part shafts of the drive shaft. At the outer ends of the two part shafts are located cam disks which serve as conversion gears and convert the rotational movement of the electromotive rotary drive into a reciprocating movement of the reed shaft. In EP 1 312 709 A1, particular reference is made to the advantage to be afforded by the symmetrical design of the drive with the arrangement of the electromotive rotary drive in the plane of symmetry of the loom running in the longitudinal direction. It is in this case considered particularly important that the torsion of two part shafts is, overall, lower than the torsion of a continuous overall shaft of double the length of a part shaft. It is also already pointed out that the torsional and flexural stress on the drive shaft presents a problem, as do inertia forces and the risk of vibration problems. In this context, it is proposed to arrange the single electromotive rotary drive in a “barycentric” position, in which the stress due to inertia forces is to be the lowest. However, this barycentric arrangement is likewise to be adapted to the arrangement in the longitudinal center of the loom which is considered the greatest advantage and the actual feature of the solution of this known reed drive.